1. Field of the Invention
The present invention relates generally to high speed data transmission systems. More particularly, embodiments of the present invention relate to systems and devices that integrate post-amplifier and laser driver functionality with a digital control interface within a single integrated circuit, thereby resulting in reduced manufacturing costs as well as improvements in operational efficiency and functionality.
2. Related Technology
Many high speed data transmission networks rely on optical transceivers and similar devices for facilitating transmission and reception of digital data embodied in the form of optical signals. Typically, data transmission in such networks is implemented by way of an optical transmitter, such as a laser, while data reception is generally implemented by way of an optical receiver, an example of which is a photodiode.
Various other components are also employed by the optical transceiver to aid in the control of the optical transmit and receive components, as well as the processing of various data and other signals. For example, such optical transceivers typically include a driver configured to control the operation of the optical transmitter in response to various control inputs. The optical transceiver also generally includes an amplifier configured to perform various operations with respect to certain parameters of a data signal received by the optical receiver.
In conventional optical transceivers, the driver and amplifier are implemented by way of separate integrated circuits (“IC”) that are placed on a printed circuit board (“PCB”) and electrically connected with each other and with the optical transmitter and receiver. One drawback to such an approach however, is that the two separate ICs take up a relatively large amount of space on the PCB, often necessitating the use of a two-sided PCB. This type of approach is problematic however, at least because such two-sided PCBs are generally more expensive and more difficult to manufacture than a single-sided PCB.
Another concern with conventional optical transceivers relates to the control circuit interface typically employed. Generally, the control circuit serves to direct both the processing of various data signals, as well as certain operational aspects of the optical transmitter and receiver. In conventional optical transceivers, the driver and post-amplifier communicate with the control circuit by way of corresponding analog interfaces. One problem with such an arrangement is that the need for multiple interfaces necessarily requires additional PCB space and complicates the manufacturing process.
As suggested by the foregoing, the implementation of post-amplifier and driver functionality in the form of discrete components gives rise to some redundancy in terms of the various components that are required. In addition to necessitating, for example, multiple interfaces, such arrangements also typically require respective sets of registers and monitoring circuits for the post-amplifier and for the laser driver. As in the case of the interfaces, these additional components take up additional space on the PCB and increase manufacturing costs and complexity.
With more particular reference to the analog interfaces between the control circuit and the post-amplifier and laser driver, it was suggested earlier that implementation of such analog interfaces requires the control circuit to communicate with the optical transceivers by way of analog signals. However, the use of such analog signals, at least where such use is required by the employment of analog interfaces, may limit the functionality of the control circuit and/or the optical transceiver.
In view of the foregoing, it would be useful to be able to integrate the post-amplifier and laser driver in such a way that their respective functionalities could be implemented in a single-sided PCB, while at the same time minimizing redundant components and functionality. Moreover, the integrated post-amplifier and laser driver should include a single digital control interface that will serve to enhance the flexibility and functionality of the optical transceiver, and related devices, by providing the ability to receive and process multiplexed digital control signals that include data pertaining to a variety of signal control parameters. Finally, the integrated post-amplifier and laser driver should implement suitable digital-to-analog converters (“DAC”) which will allow conversion of digital control signals to an analog form that that can be used in the processing of various data signals, as well as in the control of certain operational aspects of the optical transmitter and optical receiver.